This invention relates to metallurgical vessels and more particularly to a converter vessel having a plurality of tuyeres each connected for receiving various process materials.
One type of metallurgical vessel for converting pig iron to steel, called a Q-BOP, includes one or more two-pipe tuyeres which extend through the refractory lining in the lower end of the vessel for delivering oxygen to molten ferrous metal contained therein. In order to prevent the rapid deterioration of the tuyeres and the surrounding refractory, a hydrocarbon fluid, such as propane, natural gas, coal gas or light oil is injected through the gap between the inner and outer concentric tuyere pipes to provide a protective sheath in surrounding relation to the oxygen stream.
Q-BOP vessel bottom tuyeres are also used for preheating the metallic charge which may contain solid material, such as scrap metal, sponge iron, prereduced iron pellets. When the tuyeres are used for normal oxygen blowing, the ratio of hydrocarbon to oxygen is relatively small and, accordingly, the gap between the inner and outer tuyere pipes is correspondingly small in relation to the area of the center pipe through which the oxygen is delivered. This limits the volume of fuel that can be delivered during preheating. As a result, heavier hydrocarbons, such as oil, or powdered carbon are used as a preheating fuel even though a gas is normally employed during the main oxygen blow.
It will also be appreciated that because the vessel pivots, it is necessary to deliver the required gases, liquids and particulate material from fixed to rotary piping. Normally, cooling water and the hydrocarbons are delivered in separate flow paths through a first trunnion pin and oxygen is delivered through the other pin to prevent accidental mixing of oxygen with any of the process fluids. It is also desirable in such vessels to individually control various gases, liquids and fluid entrained solids for delivery to the vessel during various portions of the operating cycle. This requires a multiplicity of individual pipes connected to flow passges in the trunnion pins and between the trunnion pins and the tuyeres.